Vulnerable brain regions in adolescent major depressive disorder:A resting-state functional magnetic resonance imaging activation likelihood estimation meta-analysis

BACKGROUND Adolescent major depressive disorder(MDD)is a significant mental health concern that often leads to recurrent depression in adulthood.Resting-state functional magnetic resonance imaging(rs-fMRI)offers unique insights into the neural mechanisms underlying this condition.However,despite previous research,the specific vulnerable brain regions affected in adolescent MDD patients have not been fully elucidated.AIM To identify consistent vulnerable brain regions in adolescent MDD patients using rs-fMRI and activation likelihood estimation(ALE)meta-analysis.METHODS We performed a comprehensive literature search through July 12,2023,for studies investigating brain functional changes in adolescent MDD patients.We utilized regional homogeneity(ReHo),amplitude of low-frequency fluctuations(ALFF)and fractional ALFF(fALFF)analyses.We compared the regions of aberrant spontaneous neural activity in adolescents with MDD vs healthy controls(HCs)using ALE.RESULTS Ten studies(369 adolescent MDD patients and 313 HCs)were included.Combining the ReHo and ALFF/fALFF data,the results revealed that the activity in the right cuneus and left precuneus was lower in the adolescent MDD patients than in the HCs(voxel size:648 mm3,P<0.05),and no brain region exhibited increased activity.Based on the ALFF data,we found decreased activity in the right cuneus and left precuneus in adolescent MDD patients(voxel size:736 mm3,P<0.05),with no regions exhibiting increased activity.CONCLUSION Through ALE meta-analysis,we consistently identified the right cuneus and left precuneus as vulnerable brain regions in adolescent MDD patients,increasing our understanding of the neuropathology of affected adolescents.

Alteration of functional connectivity in patients with Alzheimer’s disease revealed by resting-state functional magnetic resonance imaging

The main symptom of patients with Alzheimer’s disease is cognitive dysfunction. Alzheimer’s disease is mainly diagnosed based on changes in brain structure. Functional connectivity reflects the synchrony of functional activities between non-adjacent brain regions, and changes in functional connectivity appear earlier than those in brain structure. In this study, we detected resting-state functional connectivity changes in patients with Alzheimer’s disease to provide reference evidence for disease prediction. Functional magnetic resonance imaging data from patients with Alzheimer’s disease were used to show whether particular white and gray matter areas had certain functional connectivity patterns and if these patterns changed with disease severity. In nine white and corresponding gray matter regions, correlations of normal cognition, early mild cognitive impairment, and late mild cognitive impairment with blood oxygen level-dependent signal time series were detected. Average correlation coefficient analysis indicated functional connectivity patterns between white and gray matter in the resting state of patients with Alzheimer’s disease. Functional connectivity pattern variation correlated with disease severity, with some regions having relatively strong or weak correlations. We found that the correlation coefficients of five regions were 0.3–0.5 in patients with normal cognition and 0–0.2 in those developing Alzheimer’s disease. Moreover, in the other four regions, the range increased to 0.45–0.7 with increasing cognitive impairment. In some white and gray matter areas, there were specific connectivity patterns. Changes in regional white and gray matter connectivity patterns may be used to predict Alzheimer’s disease;however, detailed information on specific connectivity patterns is needed. All study data were obtained from the Alzheimer’s Disease Neuroimaging Initiative Library of the Image and Data Archive Database.

Small-worldness of brain networks after brachial plexus injury: a resting-state functional magnetic resonance imaging study

Research on brain function after brachial plexus injury focuses on local cortical functional reorganization,and few studies have focused on brain networks after brachial plexus injury.Changes in brain networks may help understanding of brain plasticity at the global level.We hypothesized that topology of the global cerebral resting-state functional network changes after unilateral brachial plexus injury.Thus,in this cross-sectional study,we recruited eight male patients with unilateral brachial plexus injury（right handedness,mean age of 27.9±5.4years old）and eight male healthy controls（right handedness,mean age of 28.6±3.2）.After acquiring and preprocessing resting-state magnetic resonance imaging data,the cerebrum was divided into 90 regions and Pearson’s correlation coefficient calculated between regions.These correlation matrices were then converted into a binary matrix with affixed sparsity values of 0.1–0.46.Under sparsity conditions,both groups satisfied this small-world property.The clustering coefficient was markedly lower,while average shortest path remarkably higher in patients compared with healthy controls.These findings confirm that cerebral functional networks in patients still show smallworld characteristics,which are highly effective in information transmission in the brain,as well as normal controls.Alternatively,varied small-worldness suggests that capacity of information transmission and integration in different brain regions in brachial plexus injury patients is damaged.

Survivors of COVID-19 exhibit altered amplitudes of low frequency fluctuation in the brain: a resting-state functional magnetic resonance imaging study at 1-year follow-up

Although some short-term follow-up studies have found that individuals recovering from coronavirus disease 2019(COVID-19)exhibit anxiety,depression,and altered brain microstructure,their long-term physical problems,neuropsychiatric sequelae,and changes in brain function remain unknown.This observational cohort study collected 1-year follow-up data from 22 patients who had been hospitalized with COVID-19(8 males and 11 females,aged 54.2±8.7 years).Fatigue and myalgia were persistent symptoms at the 1-year follow-up.The resting state functional magnetic resonance imaging revealed that compared with 29 healthy controls(7 males and 18 females,aged 50.5±11.6 years),COVID-19 survivors had greatly increased amplitude of low-frequency fluctuation(ALFF)values in the left precentral gyrus,middle frontal gyrus,inferior frontal gyrus of operculum,inferior frontal gyrus of triangle,insula,hippocampus,parahippocampal gyrus,fusiform gyrus,postcentral gyrus,inferior parietal angular gyrus,supramarginal gyrus,angular gyrus,thalamus,middle temporal gyrus,inferior temporal gyrus,caudate,and putamen.ALFF values in the left caudate of the COVID-19 survivors were positively correlated with their Athens Insomnia Scale scores,and those in the left precentral gyrus were positively correlated with neutrophil count during hospitalization.The long-term follow-up results suggest that the ALFF in brain regions related to mood and sleep regulation were altered in COVID-19 survivors.This can help us understand the neurobiological mechanisms of COVID-19-related neuropsychiatric sequelae.This study was approved by the Ethics Committee of the Second Xiangya Hospital of Central South University(approval No.2020 S004)on March 19,2020.

Altered spontaneous brain activity in patients with diabetic optic neuropathy:A resting-state functional magnetic resonance imaging study using regional homogeneity

BACKGROUND Diabetes is a common chronic disease.Given the increasing incidence of diabetes,more individuals are affected by diabetic optic neuropathy(DON),which results in decreased vision.Whether DON leads to abnormalities of other visual systems,including the eye,the visual cortex,and other brain regions,remains unknown.AIM To investigate the local characteristics of spontaneous brain activity using regional homogeneity(ReHo)in patients with DON.METHODS We matched 22 patients with DON with 22 healthy controls(HCs).All subjects underwent resting-state functional magnetic resonance imaging.The ReHo technique was used to record spontaneous changes in brain activity.Receiver operating characteristic(ROC)curves were applied to differentiate between ReHo values for patients with DON and HCs.We also assessed the correlation between Hospital Anxiety and Depression Scale scores and ReHo values in DON patients using Pearson correlation analysis.RESULTS ReHo values of the right middle frontal gyrus(RMFG),left anterior cingulate(LAC),and superior frontal gyrus(SFG)/left frontal superior orbital gyrus(LFSO)were significantly lower in DON patients compared to HCs.Among these,the greatest difference was observed in the RMFG.The result of the ROC curves suggest that ReHo values in altered brain regions may help diagnose DON,and the RMFG and LAC ReHo values are more clinically relevant than SFG/LFSO.We also found that anxiety and depression scores of the DON group were extremely negatively correlated with the LAC ReHo values(r=-0.9336,P<0.0001 and r=-0.8453,P<0.0001,respectively).CONCLUSION Three different brain regions show ReHo changes in DON patients,and these changes could serve as diagnostic and/or prognostic biomarkers to further guide the prevention and treatment of DON patients.

Brain mechanism of acupuncture for children with anisometropic amblyopia: a resting functional magnetic resonance imaging study based on voxel-mirrored homotopic connectivity

AIM:To explore the brain mechanism of acupuncture for children with anisometropic amblyopia using the voxelmirror homotopic connectivity(VMHC)analysis method of resting functional magnetic resonance imaging(rs-fMRI)technology based on clinical effectiveness.METHODS:Eighty children with anisometropic monocular amblyopia were randomly divided into two groups:control(40 cases,1 case of shedding)and acupuncture(40 cases,1 case of shedding)groups.The control group was treated with glasses,red flash,grating,and visual stimulations,with each procedure conducted for 5min per time.Based on routine treatment,the acupuncture group underwent acupuncture of“regulating qi and unblocking meridians to bright eyes”,Jingming(BL1),Cuanzhu(BL2),Guangming(GB37),Fengchi(GB20)acupoints were taken on both sides,with the needle kept for 30min each time.Both groups were treated once every other day,three times per week,for a total of 4wk.After the treatment,the overall curative effect of the two groups and the latency and amplitude changes of P100 wave of pattern visual-evoked potential were counted.At the same time,nine children with left eye amblyopia were randomly selected from the two groups and were scanned with rsfMRI before and after treatment.The differences in the brain regions between the two groups were compared and analyzed with VMHC.RESULTS:Chi-square test showed a notable difference in the total efficiency rate between the acupuncture(94.87%)and control groups(79.49%).Regarding the P100 wave latency and amplitude,the acupuncture group had significantly shorter latency and higher amplitude of P100 wave than the control group.Moreover,the VMHC values of the bilateral temporal lobe,superior temporal gyrus,and middle temporal gyrus were notably increased in the acupuncture group after treatment.CONCLUSION:Acupuncture combined with conventional treatment can significantly improve the corrected visual acuity and optic nerve conduction in children with anisometropic amblyopia.Compared with the conventional treatment,the regulation of acupuncture on the functional activities of the relevant brain areas in the anterior cerebellum may be an effective acupuncture mechanism for anisometropic amblyopia.

Advancements in Functional Magnetic Resonance Imaging for Persistent Postural-Perceptual Dizziness

Persistent postural-perceptual dizziness, defined in 2017, is a chronic functional vestibular disorder. Which is characterized by persistent dizziness, unsteadiness, and/or non-spinning vertigo. However, the exact mechanisms remain unclear. In recent years, FMRI studies have provided key insights into the pathogenesis of PPPD. This review summarized functional imaging studies of persistent postural dizziness and its predecessors in recent years and found changes in the activity and functional connectivity of important areas of visual processing, multisensory vestibular and spatial cognition in patients with PPPD. In addition, factors such as stimulation mode, personality traits, mental comorbidities and external vestibular lesions have important effects on brain functional activities and connectivity patterns, and further stratified studies on these factors are needed in the future to further clarify and draw exact conclusions on the pathological mechanism of PPPD.

Abnormal intrinsic brain activity in amnestic mild cognitive impairment revealed by amplitude of low-frequency fluctuation： a resting-state functional magnetic resonance imaging study

Background Previous studies have shown that brain functional activity in the resting state is impaired in Alzheimer＇s disease （AD） patients. However, alterations in intrinsic brain activity patterns in mild cognitive impairment （MCI） patients are poorly understood. This study aimed to explore the differences in regional intrinsic activities throughout the whole brain between aMCI patients and controls. Methods In the present study, resting-state functional magnetic resonance imaging （fMRI） was performed on 18 amnestic MCI （aMCI） patients, 18 mild AD patients and 20 healthy elderly subjects. And amplitude of low-frequency fluctuation （ALFF） method was used. Results Compared with healthy elderly subjects, aMCI patients showed decreased ALFF in the right hippocampus and parahippocampal cortex, left lateral temporal cortex, and right ventral medial prefrontal cortex （vMPFC） and increased ALFF in the left temporal-parietal junction （TPJ） and inferior parietal Iobule （IPL）. Mild AD patients showed decreased ALFF in the left TPJ, posterior IPL （plPL）, and dorsolateral prefrontal cortex compared with aMCI patients. Mild AD patients also had decreased ALFF in the right posterior cingulate cortex, right vMPFC and bilateral dorsal MPFC （dMPFC） compared with healthy elderly subjects. Conclusions Decreased intrinsic activities in brain regions closely related to episodic memory were found in aMCI and AD patients. Increased TPJ and IPL activity may indicate compensatory mechanisms for loss of memory function in aMCI patients. These findings suggest that the fMRI based on ALFF analysis may provide a useful tool in the study of aMCI patients.

Structural and functional alterations in the brains of patients with anisometropic and strabismic amblyopia:a systematic review of magnetic resonance imaging studies

Amblyopia is the most common cause of vision loss in children and can persist into adulthood in the absence of effective intervention.Previous clinical and neuroimaging studies have suggested that the neural mechanisms underlying strabismic amblyopia and anisometropic amblyopia may be different.Therefore,we performed a systematic review of magnetic resonance imaging studies investigating brain alterations in patients with these two subtypes of amblyopia;this study is registered with PROSPERO(registration ID:CRD42022349191).We searched three online databases(PubMed,EMBASE,and Web of Science) from inception to April 1,2022;39 studies with 633 patients(324patients with anisometropic amblyo pia and 309 patients with strabismic amblyopia) and 580 healthy controls met the inclusion criteria(e.g.,case-control designed,pee r-reviewed articles) and were included in this review.These studies highlighted that both strabismic amblyopia and anisometropic amblyopia patients showed reduced activation and distorted topological cortical activated maps in the striate and extrastriate co rtices during tas k-based functional magnetic resonance imaging with spatial-frequency stimulus and retinotopic representations,respectively;these may have arisen from abnormal visual experiences.Compensations for amblyopia that are reflected in enhanced spontaneous brain function have been reported in the early visual cortices in the resting state,as well as reduced functional connectivity in the dorsal pathway and structural connections in the ventral pathway in both anisometro pic amblyopia and strabismic amblyopia patients.The shared dysfunction of anisometro pic amblyopia and strabismic amblyopia patients,relative to controls,is also chara cterized by reduced spontaneous brain activity in the oculomotor co rtex,mainly involving the frontal and parietal eye fields and the cerebellu m;this may underlie the neural mechanisms of fixation instability and anomalous saccades in amblyopia.With regards to specific alterations of the two forms of amblyo pia,anisometropic amblyo pia patients suffer more microstructural impairments in the precortical pathway than strabismic amblyopia patients,as reflected by diffusion tensor imaging,and more significant dysfunction and structural loss in the ventral pathway.Strabismic amblyopia patients experience more attenuation of activation in the extrastriate co rtex than in the striate cortex when compared to anisometropic amblyopia patients.Finally,brain structural magnetic resonance imaging alterations tend to be lateralized in the adult anisometropic amblyopia patients,and the patterns of brain alterations are more limited in amblyopic adults than in childre n.In conclusion,magnetic resonance imaging studies provide important insights into the brain alterations underlying the pathophysiology of amblyopia and demonstrate common and specific alte rations in anisometropic amblyo pia and strabismic amblyopia patients;these alterations may improve our understanding of the neural mechanisms underlying amblyopia.

An association study of protein tyrosine phosphatase receptor type R gene polymorphism and the resting-state functional magnetic resonance imaging in major depressive disorder

Objective To explore the influence of a polymorphism of protein tyrosine phosphatase receptor type R(PTPRR)gene rs1513105 on abnormal brain activities in resting-state patients with major depressive disorder(MDD)using the gene-imaging technology.Methods 54MDD and 43 gender-,age-,and education-matched con-

Functional magnetic resonance imaging study of group independent components underpinning item responses to paranoid-depressive scale

BACKGROUND Our study expand upon a large body of evidence in the field of neuropsychiatric imaging with cognitive,affective and behavioral tasks,adapted for the functional magnetic resonance imaging(MRI)(fMRI)experimental environment.There is sufficient evidence that common networks underpin activations in task-based fMRI across different mental disorders.AIM To investigate whether there exist specific neural circuits which underpin differ-ential item responses to depressive,paranoid and neutral items(DN)in patients respectively with schizophrenia(SCZ)and major depressive disorder(MDD).METHODS 60 patients were recruited with SCZ and MDD.All patients have been scanned on 3T magnetic resonance tomography platform with functional MRI paradigm,comprised of block design,including blocks with items from diagnostic paranoid(DP),depression specific(DS)and DN from general interest scale.We performed a two-sample t-test between the two groups-SCZ patients and depressive patients.Our purpose was to observe different brain networks which were activated during a specific condition of the task,respectively DS,DP,DN.RESULTS Several significant results are demonstrated in the comparison between SCZ and depressive groups while performing this task.We identified one component that is task-related and independent of condition(shared between all three conditions),composed by regions within the temporal(right superior and middle temporal gyri),frontal(left middle and inferior frontal gyri)and limbic/salience system(right anterior insula).Another com-ponent is related to both diagnostic specific conditions(DS and DP)e.g.It is shared between DEP and SCZ,and includes frontal motor/language and parietal areas.One specific component is modulated preferentially by to the DP condition,and is related mainly to prefrontal regions,whereas other two components are significantly modulated with the DS condition and include clusters within the default mode network such as posterior cingulate and precuneus,several occipital areas,including lingual and fusiform gyrus,as well as parahippocampal gyrus.Finally,component 12 appeared to be unique for the neutral condition.In addition,there have been determined circuits across components,which are either common,or distinct in the preferential processing of the sub-scales of the task.CONCLUSION This study has delivers further evidence in support of the model of trans-disciplinary cross-validation in psychiatry.

RESTplus: an improved toolkit for resting-state functional magnetic resonance imaging data processing

Resting-state functional magnetic resonance imaging (RS-fMRI)[1,2] provides relatively high spatial and temporal resolution for mapping spontaneous brain activity non-invasively. It has been widely used in cognitive neuroscience and clinical studies. A number of comprehensive software packages have been developed for RS-fMRI data analysis, among which a MATLAB package named REST (RESing-state fMRI data analysis Toolkit, released in October 2008 at http://www.restfmri.net)[3] is the earliest one dedicated to RS-fMRI analysis. REST focuses on RS-fMRI postprocessing metrics.

Decreased regional homogeneity in major depression as revealed by resting-state functional magnetic resonance imaging

Backgroud Functional imaging studies indicate abnormal activities in cortico-limbic network in depression during either task or resting state. The present work was to explore the abnormal spontaneous activity shown with regional homogeneity （ReHo） in depression by resting-state functional magnetic resonance imaging （fMRI）.Methods Using fMRI, the differences of regional brain activity were measured in resting state in depressed vs. healthy participants. Sixteen participants firstly diagnosed with major depressive disorder and 16 controls were scanned during resting state. A novel method based on ReHo was used to detect spontaneous hemodynamic responses across the whole brain.Results ReHo in the left thalamus, left temporal lobe, left cerebellar posterior lobe, and the bilateral occipital lobe was found to be significantly decreased in depression compared to healthy controls in resting state of depression.Conclusions Abnormal spontaneous activity exists in the left thalamus, left temporal lobe, left cerebellar posterior lobe,and the bilateral occipital lobe. And the ReHo may be a potential reference in understanding the distinct brain activity in resting state of depression.

Altered regional homogeneity in post-traumatic stress disorder: a resting-state functional magnetic resonance imaging study

Objective Little is known about the brain systems that contribute to vulnerability to post-traumatic stress disorder （PTSD）. Comparison of the resting-state patterns of intrinsic functional synchronization, as measured by functional magnetic resonance imaging （fMRI）, between groups with and without PTSD following a traumatic event can help identify the neural mechanisms of the disorder and targets for intervention. Methods Fifty-four PTSD patients and 72 matched traumatized subjects who experienced the 2008 Sichuan earthquake were imaged with blood oxygen level-dependent （BOLD） fMRI and analyzed using the measure of regional homogeneity （ReHo） during the resting state. Results PTSD patients presented enhanced ReHo in the left inferior parietal lobule and right superior frontal gyrus, and reduced ReHo in the right middle temporal gyrus and lingual gyrus, relative to traumatized individuals without PTSD. Conclusion Our findings showed that abnormal brain activity exists under resting conditions in PTSD patients who had been exposed to a major earthquake. Alterations in the local functional connectivity of cortical regions are likely to contribute to the neural mechanisms underlying PTSD.

Amplitude of Low-frequency Oscillations in Parkinson＇s Disease： A 2-year Longitudinal Resting-state Functional Magnetic Resonance Imaging Study

Background：Neuroimaging studies have found that functional changes exist in patients with Parkinson＇s disease （PD）.However,the majority of functional magnetic resonance imaging （fMRI） studies in patients with PD are task-related and cross-sectional.This study investigated the functional changes observed in patients with PD,at both baseline and after 2 years,using resting-state fMRI.It further investigated the relationship between whole-brain spontaneous neural activity of patients with PD and their clinical characteristics.Methods：Seventeen patients with PD underwent an MRI procedure at both baseline and after 2 years using resting-state fMRI that was derived from the same 3T MRI.In addition,20 age-and sex-matched,healthy controls were examined using resting-state fMRI.The fractional amplitude of low-frequency fluctuation （fALFF） approach was used to analyze the fMRI data.Nonlinear registration was used to model within-subject changes over the scanning interval,as well as changes between the patients with PD and the healthy controls.A correlative analysis between the fALFF values and clinical characteristics was performed in the regions showing fALFF differences.Results：Compared to the control subjects,the patients with PD showed increased fALFF values in the left inferior temporal gyrus,right inferior parietal lobule （IPL） and right middle frontal gyrus.Compared to the baseline in the 2 years follow-up,the patients with PD presented with increased fALFF values in the right middle temporal gyrus and right middle occipital gyrus while also having decreased fALFF values in the right cerebellum,right thalamus,right striatum,left superior parietal lobule,left IPL,left precentral gyrus,and left postcentral gyrus （P 〈 0.01,after correction with AlphaSim）.In addition,the fALFF values in the right cerebellum were positively correlated with the Unified PD Rating Scale （UPDRS） motor scores （r =0.5 l,P 〈 0.05,uncorrected） and the change in the UPDRS motor score （r =0.61,P 〈 0.05,uncorrected）.Conclusions：The baseline and longitudinal changes of the fALFF values in our study suggest that dysfunction in the brain may affect the regions related to cortico-striato-pallido-thalamic loops and cerebello-thalamo-cortical loops as the disease progresses and that alterations to the spontaneous neural activity of the cerebellum may also play an important role in the disease＇s progression in patients with PD.

Regional homogeneity analysis on acupoint specificity with resting-state functional magnetic resonance imaging

Background The mechanism of acupuncture analgesia in craniotomy has been widely studied. However, the theoretical basis for selection of acupoints has not been examined. In this study, we used the regional homogeneity method blood oxygen level-dependent （BOLD） signals to determine changes in brain activity in response to transcutaneous electrical stimulation on acupoints and non-acupoints in resting state functional magnetic resonance imaging （fMRI）.Methods Twelve healthy volunteers were enrolled in this study. BOLD fMRI scanning of the brain was performed for 306 seconds before and 30 minutes after transcutaneous electrical stimulation on acupoints UB63 （Jinmen）, LV3 （Tai chong）, ST36 （Zusanli）, and GB40 （Qiuxu）. The procedure was repeated after one week with stimulation on non-acupoints （one was 9 above BL67, the second was 12 above BL67 （Kunlun）, the third was 7 above KI3, and the fourth was 10 above KI3 （Taixi））.Results The regional homogeneity in the acupoint group was increased in the left thalamus, caudate, putamen, lentiform nucleus （BA19, 30, 39）, postcentral gyrus, precentral gyrus （BA3, 4, 30, 32）, calcarine fissure, middle temporal gyrus （BA30）, right superior temporal gyrus, inferior temporal gyrus （BA38）, cuneus, and precuneus （BA7, 19） when compared to the non-acupoint group. The regional homogeneity of the acupoint group was decreased in the left cerebellum posterior lobe, middle frontal gyrus （BA10）, double-side precuneus （BA7）, and the postcentral gyrus （BA40）.Conclusions The brain region activated following acupoint stimulation is the ipsilateral pain-related brain region, which may relate to the therapeutic effect of acupuncture on pain relief. Further acupoint stimulation causes different central nervous responses compared to non-acupoint stimulation.

Altered regional homogeneity in spontaneous cluster headache attacks： a resting-state functional magnetic resonance imaging study

Background Functional neuroimaging study has opened an avenue for exploring the pathophysiology of cluster headache （CH）.The aim of our study was to assess the changes in brain activity in CH patients by the regional homogeneity method using resting-state functional magnetic resonance imaging technique.Methods The functional magnetic resonance imaging scans were obtained for 12 male CH patients with spontaneous right-sided headache attacks during “in attack” and “out of attack” periods and 12 age- and sex-matched normal controls.The data were analyzed to detect the altered brain activity by the regional homogeneity method using statistical parametric mapping software.Results Altered regional homogeneity was detected in the anterior cingulate cortex,the posterior cingulate cortex,the prefrontal cortex,insular cortex,and other brain regions involved in pain processing and modulation among different groups.Conclusion It is referred that these brain regions with altered regional homogeneity might be related to the pain processing and modulation of CH.

Abnormal brain activity in rats with sustained hypobaric hypoxia exposure:a resting-state functional magnetic resonance imaging study

Background:Hypobaric hypoxia(HH)exposure at high altitudes can result in a decline in cognitive function,which may have a serious impact on the daily life of people who migrate to high altitudes.However,the specific HH-induced changes in brain function remain unclear.This study explored changes in brain activity in rats exposed to a sustained HH environment using functional magnetic resonance imaging(fMRI).Methods:Healthy male rats(8 weeks old)were randomly divided into a model group and a control group.A rat model of cognitive impairment induced by sustainedHHexposure was established.The control and model groups completed training and testing in the Morris water maze(MWM).A two-sample t-test for between-group difference comparisons was performed.Repeated measures analyses of variance for within-group comparisons were performed and post-hoc comparisons were made using the Tukey test.Between-group differences in spontaneous brain activity were assessed using a voxel-wise analysis of resting-state fMRI(rs-fMRI),combined with analyses of the fractional amplitude of low frequency fluctuations(fALFF)in statistical parametric mapping.Results:In the MWM test,the escape latencies of the model group were significantly longer compared with those of the control group(control group vs.model group,day 1:21.6±3.3 s vs.40.5±3.4 s,t=–11.282;day 2:13.5±2.2 s vs.28.7±5.3 s,t=–7.492;day 3:10.5±2.8 s vs.22.6±6.1 s,t=–5.099;day 4:9.7±2.5 s vs.18.6±5.2 s,t=–4.363;day 5:8.8±2.7 s vs.16.7±5.0 s,t=–3.932;all P<0.001).Within both groups,the escape latency at day 5 was significantly shorter than those at other time points(control group:F=57.317,P<0.001;model group:F=50.718,P<0.001).There was no within-group difference in average swimming speed(control group,F=1.162,P=0.956;model group,F=0.091,P=0.880).Within the model group,the time spent within the original platform quadrant was significantly shorter(control group vs.model group:36.1±5.7 s vs.17.8±4.3 s,t=7.249,P<0.001)and the frequency of crossing the original platform quadrant was significantly reduced(control group vs.model group:6.4±1.9 s vs.2.0±0.8 s,t=6.037,P<0.001)compared with the control group.In the rs-fMRI study,compared with the control group,rats in the model group showed widespread reductions in fALFF values throughout the brain.Conclusions:The abnormalities in spontaneous brain activity indicated by the fALFF measurements may reflect changes in brain function after HH exposure.This widespread abnormal brain activity may help to explain and to provide new insights into the mechanism underlying the impairment of brain function under sustained exposure to high altitudes.

Influence of three different anesthesia protocols on aged rat brain:a resting-state functional magnetic resonance imaging study

Background:Resting-state functional magnetic resonance imaging(rs-fMRI)is a promising method for the study of brain function.Typically,rs-fMRI is performed on anesthetized animals.Although different functional connectivity(FC)in various anesthetics on whole brain have been studied,few studies have focused on different FC in the aged brain.Here,we measured FC under three commonly used anesthesia methods and analyzed data to determine if the FC in whole brain analysis were similar among groups.Methods:Twenty-four male aged Wistar rats were randomly divided into three groups(n=8 in each group).Anesthesia was performed under either isoflurane(ISO),combined ISO+dexmedetomidine(DEX)orα-chloralose(AC)according to the groups.Data of rs-fMRI was analyzed by FC in a voxel-wise way.Differences in the FC maps between the groups were analyzed by one-way analysis of variance andpost hoc two-samplet tests.Results:Compared with ISO+DEX anesthesia,ISO anesthesia caused increased FC in posterior brain and decreased FC in the middle brain of the aged rat.AC anesthesia caused global suppression as no increase in FC was observed.Conclusion:ISO could be used as a substitute for ISO+DEX in rat default mode network studies if the left temporal association cortex is not considered important.

Aphasia rehabilitation based on mirror neuron theory: a randomized-block-design study of neuropsychology and functional magnetic resonance imaging

When watching someone performs an action, mirror neurons are activated in a way that is very similar to the activation that occurs when actually performing that action. Previous single-sample case studies indicate that hand-action observation training may lead to activation and remodeling of mirror neuron systems, which include important language centers, and may improve language function in aphasia patients. In this randomized-block-design experiment, we recruited 24 aphasia patients from, Zhongda Hospital, Southeast University, China. The patients were divided into three groups where they underwent hand-action observation and repetition, dynamic-object observation and repetition, or conventional speech therapy. Training took place 5 days per week, 35 minutes per day, for 2 weeks. We assessed language function via picture naming tests for objects and actions and the Western Aphasia Battery. Among the participants, one patient, his wife and four healthy student volunteers underwent functional magnetic resonance imaging to analyze changes in brain activation during hand-action observation and dynamic-object observation. Results demonstrated that, compared with dynamic-object observation, hand-action observation led to greater performance with respect to the aphasia quotient and affiliated naming sub-tests and a greater Western Aphasia Battery test score. The overall effect was similar to that of conventional aphasia training, yet hand-action observation had advantages compared with conventional training in terms of vocabulary extraction and spontaneous speech. Thus, hand-action observation appears to more strongly activate the mirror neuron system compared with dynamic-object observation. The activated areas included Broca's area, Wernicke's area, and the supramarginal gyrus. These results suggest that hand-action observation combined with repetition might better improve language function in aphasia patients compared with dynamic-object observation combined with repetition. The therapeutic mechanism of this intervention may be associated with activation of additional mirror neuron systems, and may have implications for the possible repair and remodeling of damaged nerve networks. The study protocol was approved by the Ethical Committee of Nanjing Medical University, China(approval number: 2011-SRFA-086) on March 11, 2011. This trial has been registered in the ISRCTN Registry(ISRCTN84827527).